Gem County residents are subjected to a wide range of weather events, including: thunderstorms, hail, lightning, high winds, micro-bursts, winter storms, blizzards, extreme heat, drought, and others. These weather events cause property damage and injuries or deaths almost every year and at all times of the year.
A variety of hazardous substances are produced, stored, and used in Gem County. In addition, they are routinely transported on the miles of roads in the county. Commonly found chemicals include: anhydrous ammonia, chlorine, ethanol, formaldehyde, hydrofluoric acid, nitric acid, propane gas, sulfuric acid, and various petroleum products, such as gasoline.
Idaho ranks 6th highest in the nation for earthquake risk. Two of the largest quakes in the lower 48 states in the last fifty years occurred in or near Idaho and were felt in Gem County. Most buildings constructed prior to the late 1980s were built without much regard to earthquake resistance. Even moderate earthquakes can cause widespread damage to such things as buildings, roads, bridges, and water and sewer lines.
Many wildfires occur in Gem County every year. Most wildfires do not get very large before they are extinguished, but there are exceptions. In 1992 a fire blackened 257,000 acres in Ada and Boise Counties, and in 1996 the Eight Street wildfire burned 15,300 acres in the Boise Foothills. The growing wildland-urban interface increases the likelihood of structural damage and human casualties. In 2022 The Four Corners Fire in the Boise and Payette National Forest reached parts of Gem County in the wilderness above Ola and Sagehen Reservoir.
Although fire codes and fire-resistant building materials have reduced the threat, structural fires still happen all too frequently. In 2004 fire killed more Americans than all natural disasters combined. Fire-related fatalities occur on a regular basis in Gem County.
There are many Dams that effect Gem County on the Payette River. Failures could cause widespread devastation, flooding and probably high loss of life to the people and the livestock in the affected areas.
Although Idaho Power has mitigation plans in place, and have an excellent service rating, there are still major hazards that can develop with downed power lines, wildfires, flooding, and general service outages.